Malcom agreed a five-year deal to move to the Camp Nou, with a release clause expected to be fixed at €400m.
However, the Catalan giants have now swooped in and signed the Brazilian starlet for a fee in the region on £40m. The player's agent, Fernando Garcia, told Real Sport it was the decision of the French club and not the player that resulted in the late switch: "We had an agreement with Rome, then Bordeaux blocked us".
The La Liga champions had previously made reported bids of upto £55 million to sign Willian but when Chelsea rejected their bid they looked elsewhere and moved for Malcom.
Malcom is Barcelona's second Brazilian summer signing after Gremio midfielder Arthur, 21, joined in a 31-million-euro deal. He will immediately fly out to the United States to link up with his new teammates for the International Champions Cup once his medical is complete.
Malcom first arrived in Europe in 2016, joining Bordeaux from Corinthians, where he won the Brazilian title, and made nearly 100 appearances for the Ligue 1 club.
However, Sky in Italy are reporting that Barcelona have now entered the race the sign the highly-rated forward, who scored 12 goals in 38 appearances last season.